Chlamydia trachomatis is the most common sexually transmitted bacterial pathogen in the world, causing serious complications on women's reproductive health including ectopic pregnancy, pelvic inflammatory disease and infertility. C. trachomatis also causes infection of the eye resulting in inflammation and in some cases blindness. The objectives of this project are to define the epidemiology, risk factors, transmission kinetics, and pathogenesis of C. trachomatis infections in different population settings, including populations in resource constrained countries. We have used the Internet site www.iwantthekit.org (IWTK) since 2004 to offer sampling in Maryland, the District of Columbia and Alaska for chlamydia screening in over 10,000 women and over 5000 men using self-obtained vaginal swabs, penile-meatal swabs and rectal samples. Samples were also tested for gonorrhea and trichomonas. Prevalence of chlamydia for women overall was 6.3% and 7.7% in men. Both young age and Black race have been statistically associated with chlamydia positivity. Trichomonas prevalence in women was 6.1% and 2.2% in men. For rectal chlamydia in men, the overall chlamydia prevalence was 6.9% while for gonorrhea it was 4.0%. Acceptance for self-collecting penile-meatal and rectal swabs has been very high. Rectal chlamydia and gonorrhea prevalence in women were 6.3% and 0.9%, respectively. In 2004 chlamydia prevalence was 10.0% which has declined to 3.2% in 2018, an indication of a successful public health program. Recent data indicate that between 2013-17 positivity for any STI was 10.7% and 19.9% of STIs would have been missed if urogenital sampling only had been done (22.0% of male and 11.9% of female chlamydia infections.). Recently, as part of a consented-on-line study, 120 persons have requested and performed a POC HIV oral fluid test at home, with excellent satisfaction survey results. The IWTK website has over 10,000-page views per month. A pilot study has begun to add to add home collection of dried blood spots for syphilis and HIV testing for monitoring for syphilis and HIV. To study the capability for performing a point-of-care self-test for trichomonas at home, we recently enrolled 102 women who performed the mailed point-of-care trichomonas test successfully at home. The test demonstrated high accuracy and high acceptability. In addition, males and females aged 18-59 years who participated in the 2013-2014 National Health and Nutrition Examination Survey and provided a urine specimen were tested for TV infection (n = 4057). Participants were also examined for Chlamydia trachomatis (CT) infection, genital human papillomavirus (HPV) infection, and herpes simplex virus type 2 serostatus. Weighted adjusted prevalence ratios (aPRs) were estimated by multivariable Poisson regression. TV infection prevalence was 0.5% and 1.8% among males and females, respectively. TV infection prevalence was 4.2% among black males, 8.9% among black females, and 0.03% and 0.8%, respectively, among males and females of other races/ethnicities. TV infection prevalence (aPR 95% confidence interval) was positively associated with female sex (6.1 3.3-11.3), black race (vs other races/ethnicities; 7.9 3.9-16.1), older age (vs 18-24 years; 3.0 1.2-7.1 for 25- to 39-year-olds and 3.5 1.3-9.4 for 40- to 59-year-olds), having less than a high school education (vs completing high school or more; 2.0 1.0-4.1), being below the poverty level (vs at or above the poverty level; 4.0 2.1-7.7), and having 2 sexual partners in the past year (vs 0-1 sexual partners; 3.6 2.0-6.6). There were no TV and CT coinfections. Genital HPV detection was not independently associated with TV infection. Among persons aged 18-39 years, there was a significant racial disparity in all sexually transmitted infections examined, and this disparity was greatest for TV infection. Trachoma due to C. trachomatis infection is the most common cause of infectious blindness in the world. The WHO has recommended that three rounds of mass drug administration (MDA) with antibiotics be offered to control the disease in districts where the prevalence of follicular trachoma (TF) is >10% in children aged 1-9 years, with treatment coverage of at least 80%. We have conducted both surgical and antibiotic treatment intervention studies in Gambia, Niger, and Tanzania in efforts to control trachoma. However, the source of infection following mass treatment is often unknown. If migrants into a village undergoing MDA are shown to impede progress towards elimination, then a local strategy that addresses treatment of new families and a nationwide strategy that addresses migration will be needed. We therefore conducted a community-randomized, clinical trial to determine if a surveillance program that targeted newcomers and travelers, identified weekly, would result in more communities achieving levels of infection of 1%. 52 communities were randomly allocated 1:1 to the control (annual mass drug administration with azithromycin (MDA) alone if warranted) or intervention arm (annual MDA if warranted, plus a surveillance program to identify and treat newcomers and travelers). In each community, surveys were completed every six months on a random sample of 100 children ages 1-9 years for trachoma and infection. The primary outcome was the proportion of communities in the intervention arm, compared to the control arm, which had a prevalence of infection at 1% by 24 months. Intervention communities experienced an average of 110 surveillance events per month. At 24 months, 7 (27%) of 26 intervention communities achieved a prevalence of infection 1% compared to 4 (15%) of the 26 control communities (odds ratio = 26, 95%CI = 056-119). At 24 months, the average infection prevalence in the intervention communities was 48, compared to 69 in the control communities (p = 06). Despite surveillance programs for community newcomers and travelers, the proportion of intervention communities with a level of infection 1% was lower than expected and not significantly different from control communities Antimicrobial-resistant Neisseria gonorrhoeae (NG) is a global public health issue that threatens effectiveness of current treatments of NG. Increased use of nucleic acid amplification tests (NAATs) in lieu of cultures makes obtaining clinical isolates for susceptibility testing difficult and samples collected in commercial transport buffer for NAATs do not preserve viable organism, while molecular methods of assessing antibiotic susceptibility do not require viable organism. We evaluated 243 NG-positive samples in Aptima transport media including urine, oral, and rectal swabs from Nigerian men who have sex with men for markers to penicillinase-producing NG, ciprofloxacin ( GyrA and ParC mutations), and extended spectrum cephalosporins (ESCs, PenA mosaic allele X, PonA, mtrR, PorB mutations) by real-time PCR. NG DNA was recovered in 75% (183/243) of samples. Of these, 93% (171/183) were positive for at least one resistance marker. We observed a prevalence of dual resistance markers to penicillin and ciprofloxacin at 46.2% (79/171). Six percent of samples (10/171) tested positive for the PenA mosaic (allele X) ESC marker. These data indicate that antibiotic-resistant NG is common in Nigeria. Laboratory and clinical capacity building in Nigeria should include development of methods to culture NG and determine antimicrobial susceptibility.